1) Field of the Invention
The present invention relates to an image monitor apparatus which controls a camera and a lighting system.
2) Description of the Related Art
Recently, in many image monitoring systems, a plurality of images picked up by a plurality of cameras in a plurality of locations are monitored in a monitoring center in a centralized manner. In addition, needs for monitoring or surveillance of a wide area, for example, an area including roads and railroads, are growing. Further, when the monitoring is performed in the nighttime, a high-sensitivity camera and a lighting system are required in order to monitor a dark area.
In the conventional image monitoring system using a high-sensitivity camera and a lighting system, when a flashlight or car lighting is directed to the high-sensitivity camera, the entire screen may be whited out (i.e., the so-called screen white-out occurs), or blooming or smearing may occur. However, if the iris opening is narrowed, the effect of the illumination by the lighting system decreases, and the image picked up by the camera becomes dark except that an image portion produced by picking up the above external lighting is bright.
As described above, the high-sensitivity camera is more susceptible to a disturbance caused in an image picked up by the high-sensitivity camera, than the cameras having normal sensitivity, where the disturbance is caused by, for example, light incident on the camera. Therefore, in order to obtain a stable image for monitoring, the disturbance must be appropriately controlled.